The invention relates to a method of and an apparatus for checking a heterogeneous transformation process of diffusion kinetics taking place in a turbulent flow of a liquid.
Many processes in different technical fields concern a heterogeneous transformation process which takes place in a liquid. The chemical and physicochemical transformation processes taking place on certain surfaces, e.g. on limiting surfaces of different phases, e.g. in systems comprising a liquid dispersive phase and a diespergated liquid, gaseous or solid phase, on catalytical surfaces, electrodes immersed into liquid or on the wall of a liquid vessel are generally classified as heterogeneous transformation processer.
The invention relates to checking such heterogeneous transformation processes taking place in liquids, for which the following conditions are satisfied: that the liquid performs a turbulent flow and the process is characterised by diffusion kinetics. The latter means that the rate of the transformation process is determined by the rate of material transport from the inner region of the liquid to the surface being the place of the heterogeneous transformation or from this surface to the inner region of the liquid.
For checking the heterogeneous transformation processes taking place in liquids the direct methods have become the most popular. The essence of these methods lies in sampling and in aftergoing chemical or physicochemical analyses of the samples. These methods doubtless ensure the accuracy required by the technical praxis, however, on their basis the real-time intervention or control is practically impossible: in fast changing industrial conditions the direct methods can generally not serve for solving regulation problems. Sometimes sampling is difficult to realise and especially in processes wherein it could be performed only on the condition of stopping the entire process. Another special problem is to be seen in the analysis of components present in small quantities. In this case one sample is less than enough: the contents determined for different samples can differ from one another in a wide range comprising the correct value. Therefore the analysis can rely only a higher number of samples for obtaining an average value which is the better approach of the correct value the higher is the number of samples analyzed.
Another group of solutions which have become known consists of indirect methods, wherein the rate or development of the transformation process can be checked on the basis of measuring parameters depending on the concentration, as pressure, temperature, colour, sound, etc. The known methods ensure the required information promptly, but the accuracy or reliability thereof is not as high as desired for realising a control or regulation loop. In steel production a method has been known for carrying out intervention in an oxygen converter process (Baptizmanski. V. I. et al. IVUZ, Tchornaya Metallurgiya, 1982 No. 2, p. 34 to 38) which is based on an acoustic principle. The essence of this method is following the sound effect and exactly the acoustic pressure level during blowing oxygen into the molten steel bath. According to the recognition shown by the authors a rush form alteration of the acoustic pressure level is a sign of reaching a high density of the slag covering the molten steel and this density makes stopping the oxygen supply advantageous. By this measure it is possible to avoid development of harmful secondary processes, however it is impossible to obtain information on the basis of which data could be gained about the alteration of the carbon content of the steel bath.